Nasdaq-100 War Room

One page that shows the whole Nasdaq-100 at once: a heat map of its 101 stocks, the day’s biggest gains and losses, which stocks add most to the index’s move, how many stand above their averages, which pairs of stocks stopped moving together, and how option dealers are positioned in each name.

The 101 tickers of the Nasdaq-100 as Nasdaq publishes them; the list is read again every week, so a stock that joins or leaves the index appears or disappears here by itself.

While the US market is open the figures refresh about once a minute on delayed quotes (about 15 minutes behind); after the close the page shows the closing prices, and every night it is rebuilt from end-of-day data. The line under the title always says which of the three you are looking at.

Each tile is one stock. Its size is the stock’s weight in the index — which is not plain company size: the index holds its very largest names down. The weights are read from the daily holdings of a fund that tracks the index. Its colour is the change over the period you pick — today, five days, one month or this year. “Equal” draws every stock the same size, so the small names can be read too.

A stock’s change multiplied by its weight: how many percentage points of the group’s move come from that one stock. A small gain in a very heavy name can lift the group more than a large gain in a light one — which is why an index can rise while most of its stocks fall.

For every pair of stocks the page compares how closely the two moved together over the last 63 sessions (about three months) with the 252 sessions before that (a year). A pair whose correlation fell by more than 0.20 is called shifted; one that rose by 0.30 or more, strengthened. A shift is a place to look, not a proof: with three months of data a single pair’s correlation is uncertain by about a tenth either way, and among thousands of pairs a few large changes appear by chance.

They describe how the dealers who sold or bought the options must hedge. Long gamma: they trade against a move, which tends to calm it. Short gamma: they trade with the move, which can let it stretch. It is estimated from open interest after each close, and it describes positioning — it is not a forecast of direction.

Implied volatility is the size of move the option market charges for. Divided down to one day it gives a priced one-day move; the page compares the stock’s actual change with it. A stock at 2× has moved twice what its options priced for a day.

No. The page describes what prices and option positioning are, for research and education. Nothing on it is a forecast, a target or a recommendation.